/*
 * ------------------------------------------------------------------------
 *
 *  Copyright by KNIME AG, Zurich, Switzerland
 *  Website: http://www.knime.com; Email: contact@knime.com
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License, Version 3, as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses>.
 *
 *  Additional permission under GNU GPL version 3 section 7:
 *
 *  KNIME interoperates with ECLIPSE solely via ECLIPSE's plug-in APIs.
 *  Hence, KNIME and ECLIPSE are both independent programs and are not
 *  derived from each other. Should, however, the interpretation of the
 *  GNU GPL Version 3 ("License") under any applicable laws result in
 *  KNIME and ECLIPSE being a combined program, KNIME AG herewith grants
 *  you the additional permission to use and propagate KNIME together with
 *  ECLIPSE with only the license terms in place for ECLIPSE applying to
 *  ECLIPSE and the GNU GPL Version 3 applying for KNIME, provided the
 *  license terms of ECLIPSE themselves allow for the respective use and
 *  propagation of ECLIPSE together with KNIME.
 *
 *  Additional permission relating to nodes for KNIME that extend the Node
 *  Extension (and in particular that are based on subclasses of NodeModel,
 *  NodeDialog, and NodeView) and that only interoperate with KNIME through
 *  standard APIs ("Nodes"):
 *  Nodes are deemed to be separate and independent programs and to not be
 *  covered works.  Notwithstanding anything to the contrary in the
 *  License, the License does not apply to Nodes, you are not required to
 *  license Nodes under the License, and you are granted a license to
 *  prepare and propagate Nodes, in each case even if such Nodes are
 *  propagated with or for interoperation with KNIME.  The owner of a Node
 *  may freely choose the license terms applicable to such Node, including
 *  when such Node is propagated with or for interoperation with KNIME.
 * ---------------------------------------------------------------------
 *
 * History
 *   16 Sep 2019 (albrecht): created
 */
package org.knime.product.rcp.intro.json;

import java.io.IOException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Optional;

import org.apache.commons.io.IOUtils;
import org.knime.core.node.NodeLogger;
import org.osgi.framework.Bundle;
import org.osgi.framework.FrameworkUtil;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 *
 * @author Christian Albrecht, KNIME GmbH, Konstanz, Germany
 * @since 4.1
 */
public class OfflineJsonCollector {

    private static String TILES = "intro4.0/tiles";
    private static NodeLogger LOGGER = NodeLogger.getLogger(OfflineJsonCollector.class);

    private final Bundle m_bundle;
    private final ObjectMapper m_mapper;

    /**
     *
     */
    public OfflineJsonCollector() {
        m_bundle = FrameworkUtil.getBundle(this.getClass());
        m_mapper = new ObjectMapper();
    }

    String collectJson(/* some config? */) {
        return null;
    }

    /**
     * @return
     * @throws IOException
     */
    public String fetchFirstUse() throws IOException {
        return fetchAllTilesFromDir(TILES + "/first");
    }

    public String fetchAllOffline() throws IOException {
        return fetchAllTilesFromDir(TILES + "/offline");
    }

    private String fetchAllTilesFromDir(final String dir) throws IOException {
        List<URL> ttFiles = listFilesInDir(dir);
        JSONTile[] allFirstUses = ttFiles.stream().map(url -> {
            try {
                return readFile(url);
            } catch (Exception e) {
                LOGGER.error("Could not read welcome page tile " + e.getMessage(), e);
                return null;
            }
        }).map(str -> {
            JSONTile tile = new JSONTile();
            try {
                m_mapper.readerForUpdating(tile).readValue(str);
            } catch (IOException e) {
                LOGGER.error("Could not parse welcome page tile: " + e.getMessage(), e);
            }
            return tile;
        }).toArray(JSONTile[]::new);
        return m_mapper.writeValueAsString(allFirstUses);
    }

    public JSONTile fetchSingleOfflineTile(final String prefix, final boolean first) throws IOException {
        String dir = TILES + (first ? "/first" : "/offline");
        List<URL> ttFiles = listFilesInDir(dir);
        Optional<URL> categoryFile = ttFiles.stream().filter(url -> {
            String fileName = url.getFile().substring(url.getFile().lastIndexOf("/") + 1);
            return fileName.startsWith(prefix);
        }).findFirst();
        JSONTile tile = new JSONTile();
        if (categoryFile.isPresent()) {
            String tileJson = readFile(categoryFile.get());
            try {
                m_mapper.readerForUpdating(tile).readValue(tileJson);
            } catch (IOException e) {
                LOGGER.error("Could not parse welcome page tile: " + e.getMessage(), e);
            }
         }
        return tile;
    }

    private List<URL> listFilesInDir(final String dir) {
        Enumeration<URL> entries = m_bundle.findEntries(dir, "*.json", false);
        ArrayList<URL> list = Collections.list(entries);
        list.sort((e1, e2) -> e1.getPath().compareTo(e2.getPath()));
        return list;
    }

    private static String readFile(final URL url) throws IOException {
        return IOUtils.toString(url.openStream(), Charset.forName("UTF-8"));
    }

}
